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TAF not powering up

MarkS

MarkS

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10 Years
Joined
Oct 14, 2013
Messages
256
Location
Devon
So my TAF had been playing perfectly when it did a restart on a double-flip. Played a bit longer and it happened again so I assumed it was a WPC 5V reset type issue. As we have somewhat flaky power supply here, plus the game has a ColorDMD and additional Comet lighting, I thought/hoped I'd probably get away with buying a Kahr board but in the meantime I tried re-seating connectors on the power/CPU boards... oh dear, each subsequent cycle of re-seating each connector several times and then power-cycling has had the following results:

1. Resets with the first double-flip as soon as the game is started.
2. Resets with single flip as soon as the game is started.
3. ColorDMD seemed to struggle to power up then game reset within a second of finishing powerup.
4. ColorDMD wouldn't power up (random display) and game failed to power up.
5. Nothing powers up, slight hum from speaker.

Red lights are on on various boards. I'm assuming the re-seating has progressively damaged something, but what? Is there anything relatively simple (*) I can try to identify where exactly there is a problem?

(*) I don't have a multimeter and I'm not re-soldering the board or pins in situ 😬
 
Hi
It is unlikely you have made the issue worse and it will all be fixable. However, not having a multimeter means it is going to be hard to remotely support you. Is there anyone you can borrow one from?
A Kahr board would masks the issue or even add some in this case, so remove it if you haven’t done so already.
It is sounding like the power driver board needs diagnosing to check what is happening and with the right tools and experience, this is straight forward.
@Paul can make replacement board, so that is another option should you want a quick and easy fix.
 
Red lights dont mean there is a fault - they just mean (in most cases) that something is functioning. So not a bad thing!

The resets are caused by a flakey 5v power... All the Kahir board does is takes the 12v and produces a stable 5v out of it... they are used as a temporary fix at best.

If you want, i can test and check the Power driver board in a known good test rig and repair any issues if that helps - Cheaper than buying a new one (though i can supply those - they arent cheap though!)

Cheers
Paul

EDIT : oops, just seen @Calimori post above!!
 
Unfortunately, it sounds like the BR smoothing caps on the driver boards are life expiring, either 12v circuit or 5v circuit. I'm guessing in this case it's probably the 12v ones (or a flaky BR). Personally, I would just change the lot whilst the driver board is out of the machine but the new capacitors are getting expensive the days I think the last board I repaired, the replacement caps cost nearly £10. I now order larger quantities to help try and keep repair costs down.
 
Thanks for the replies. Sounds like a test/repair is the way to go then. I'll take it offline into DMs to sort out.

To help my understanding, why has it got worse each time I've re-seated everything though? Or is that a red herring and whatever is faulty (eg. BR capacitors) has rapidly degraded? I've read other comments about cracked solder, earth connections etc...

Also, again to improve my understanding please, why is the Kahr board such a bad idea? I understand there could be a worsening situation (again like BR capacitors) that it will just mask for longer, but is there not a situation where an unreliable mains supply (like we have) is causing a < 4.9V supply to "trip out" which it would solve painlessly?

(PS. I did mention the red lights on the board as in evidence the power was getting to the boards, I should type longer sentences to explain that I didn't think they were warning lights :))
 
If you have broken connectors (solder or fried), repeated plugging won't be good.
 
drhex said:
If you have broken connectors (solder or fried), repeated plugging won't be good.
Click to expand...
They looked OK to me, couldn't see anything damaged or tarnished?

Before I start trying to remove this beast, I am right in thinking the power board is this one, right?

IMG_4039.webp
 
Interesting that C4 has been replaced, however not C2..... Probably just as well - couldnt even replace it with an Axial type!

Careful of the pins on J120 (bottom left) - they look like they have been soldered onto the IDC connector. Just a little extra care taking that one out 👍
 
It might be prudent to swap your colourDMD for a normal DMD and see if stability to your game is restored.

ColourDMD's are far more sensitive to having a stabile power supply than a regular DMD or find a separate power supply (old PC supply?) for the colourDMD.
 
Moonraker said:
It might be prudent to swap your colourDMD for a normal DMD and see if stability to your game is restored.

ColourDMD's are far more sensitive to having a stabile power supply than a regular DMD or find a separate power supply (old PC supply?) for the colourDMD.
Click to expand...
Yeah disconnect the pin2DMD first they can draw a lot of current, might be putting to much load on the current system.

Move to own PSU
 
I had already tried disconnecting the ColorDMD. In case I did something wrong trying that I swapped back in the original DMD and it's no better... I tried power cycling about 10 times, one time it temporarily came up as far as the revision number on the DMD and the playfield lights, then it reset and hasn't come back again since. Usually just a dull crackle from the speaker but nothing else.

I assume I need to start psyching myself up to take that board out :eek:
 
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